Videoconference systems include a projection device that forms images on a screen from a video stream received from a remote site and an acquisition device (typically a video camera) that films an observation area to generate a stream to be sent to the remote site.
In interpersonal communication audiovisual systems, the users are filmed by the video camera and simultaneously they observe a screen on which an image of their remote correspondent is displayed.
In some systems, the video camera is placed beside or above the screen.
This filming angle yields a skewed or downward view that is not natural. Moreover, as users are looking at the screen and not at the video camera, their correspondents have the impression that they are not making eye contact as they would in a normal face-to-face conversation.
A known way to solve this problem, shown in FIG. 1, is to use a partially transparent mirror MIR placed obliquely in front of the screen ECR and reflecting toward the video camera CAM an image of the observers situated in the observation area ZO.
The virtual position of the video camera CAM can therefore be placed in the middle of the screen ECR or behind it, where the face of a remote correspondent is displayed.
However, that system has a number of disadvantages linked in particular to the overall size and weight of the oblique mirror MIR, which furthermore imposes a minimum distance between the observers and the screen ECR.
What is more, because the area that is located behind the mirror relative to the video camera (above the mirror MIR in FIG. 1) is in the field of view of the video camera through the mirror, its image is superimposed on the image of the users, which introduces artefacts that are a nuisance.
Other artefacts are caused by reflections in the mirror MIR that are also superimposed on the image displayed on the screen ECR.